Test strip for measuring tear production

ABSTRACT

Disclosed is a test strip for measuring tear production. The test strip comprises a generally flat sheet material having one end rounded to be semi-circular shaped and being printed with a folding line along which said strip is bent prior to the measurement operation. The test strip is further printed with graduation marks and a scale for indicating the amount of absorbed tear. In a preferred embodiment, provided at either one or both corners of the end opposite to the rounded end is a mark indicating that the particular test strip is used for measuring one of either the left or right eye. The sheet material is preferably made of filter paper. The test strip has no notched portion which would weaken the sheet material and yet may be folded precisely along the fold line prior to use. The graduation marks and scales printed on the test strip enable easy measurement of the length of the portion wetted by tear fluid.

CROSS-REFERENCE

This is a continuation of Ser. No. 620,441 filed Nov. 29, 1990 which isa continuation of Ser. No. 312,650 filed Feb. 17, 1989, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a test strip for measuring tearproduction, which is used by an ophthalmologist to measure the tearproduction of a patient to diagnose a disease or any other abnormalityof the eye.

2. Prior Art

Known test strips for measuring tear production include the Shirmer teartest strip which has a width of about 5 mm and a length of 42 mm, withits one end rounded to be semi-circular shaped, and having a triangularnotch at one side of the strip spaced by about 5 mm from the roundedend. The Shirmer tear test strip is used by inserting the rounded endinternally into the lower eye-lid of a patient with the rounded end bentat the notched portion, and the test result is evaluated by visuallydetermining the length of the moistened filter paper wetted within aunit measurement of time.

However, the prior art Shirmer tear test strip has a disadvantage inthat the notched portion tends to contact the eyeball or interiorsurface of the lower eye-lid which causes cause irritation or complaint,since the strip is bent at the notched portion and then insertedinternally into the lower eye-lid. The prior art Shirmer tear test striphas another disadvantage in that the moistened strip tends to breakduring the measurement operation since the width of the strip isnarrowed by the notch. A further disadvantage of the prior art Shirmertear test strip is confusion in determining whether a particular stripis used for the testing of the right or left eye of the patient, thisbeing caused by difficulty in determination of obverse or reverse sideof the filter paper. In addition, visual determination often leads to aninaccurate diagnosis, or a separate scale must be used for precisedetermination which incurs delicate operation and inconvenience inpractical application.

OBJECT AND SUMMARY OF THE INVENTION

Accordingly, an object of this invention is to provide a test stripwhich is free from the disadvantages of the conventional Shirmer teartest strip.

A more specific object of this invention is to provide a test striphaving no notched portion which would weaken the strip to often causingbreakage at that portion, by being printed with a folding line alongwhich the strip is bent or folded and further printed with graduationmarks and scales for facilitating the measurement operation.

With the aforementioned object in view, the present invention provides atest strip for measuring tear production comprising a generally flatsheet material having one end rounded to be semi-circular shaped andbeing printed with a folding line along which said strip is bent priorto the measurement operation, said strip being further printed withgraduation marks and scales for indicating the amount of absorbed tearfluid.

In a preferred embodiment, a mark is provided at either one or bothcorners of the end opposite to the rounded end for indicating that theparticular strip is used for measuring one of either the left or righteye.

In use of the test strip of this invention, the sheet material is bentalong the folding line so that the rounded end comes below the unprintedsurface of the sheet material, that is, the surface printed with thegraduation marks and scales is held upside down. Thereafter, the foldedsemi-circular end is inserted internally into the lower eye-lid and heldat that position for a predetermined time period, for example 5 minutes,to allow the strip to be wetted by tear fluid. The length of the wettedportion of the test strip is measured. When the test strip is insertedinto a normal or healthy eye, the length of the wetted portion of thestrip ranges from 10 to 30 mm, generally about 15 mm, the lengthdecreaseing as the age of the patient increases to a considerablydecreased level when the age of the patient is 60 years or more.However, it is considered that the tested eye is diseased or in abnormalcondition when the length of the wetted portion of the test stip is lessthan 5 mm. By the use of the test strip according to this invention, thewetted length of the test strip can be readily confirmed visually bymaking use of the graduation marks and scales printed thereon.

DESCRIPTION OF THE DRAWINGS

In order that the invention can be more clearly understood, convenientembodiments thereof will now be described with reference to theaccompanying drawings, in which:

FIG. 1(A) is a plan view of one embodiment of the invention;

FIG. 1(B) is a plan view showing a portion of another embodiment of theinvention;

FIG. 1(C) is a plan view showing a portion of a further embodiment ofthe invention;

FIGS. 2(A) to 2(C) are plan views showing portions of differentembodiments; and

FIG. 3 is a plan view showing a still further embodiment which includestwo test strips arranged in tandem fashion.

PREFERRED EMBODIMENTS OF THE INVENTION

Preferred embodiments of the invention will now be described in detailwith reference to the accompanying drawings.

Initially referring to FIG. 1(A), a test strip 1 is made of a generallyflat sheet material, for example elongated sheet-form filter paper. Oneend of the filter paper is rounded to be semi-circular, and a foldingline 2 is marked by dots or dashes. Graduation marks 3 and scales 4 areprinted while setting the folding line as the starting line. Furthermarks 5, which indicate that the particular test strip is used for theexamination of one of either the left or right eye, are provided at thecorner of the test strip opposite to the rounded end. Each of the marks5 may be defined by a row of small perforations or roulettes, as shownin FIG. 1(A), so that it may be cut off or the area defined thereby maybe shaded or hatched to indicate that the particular test strip has beenused for diagnosis of the left or right eye. Otherwise, as shown in FIG.2(A), marks 5' are printed at both corners so that either one of themarks 5' is shaded; or as shown in FIG. 2(B), either one of the cornersis perforated as denoted by 5'. A futher modification is shown in FIG.2(C) wherein one of either the left or right corner is preliminarily cutaway.

A still further embodiment of the invention is shown in FIG. 3, whereintwo test strips 1, 1 are arranged in tandem fashion with their ends (theends opposite to the rounded ends) contiguous with each other anddelineated by a cutting or delineation line 6 which may be a printedline or a row of perforations or roulettes. The tandem set of teststrips may be used such that one for the diagnosis of the left eye andthe other for the diagnosis of the left eye. As seen by comparing FIG. 3with FIG. 1, the graduation marks 3 and scales 4 are arranged in asomewhat different manner.

All of the marks depicted on the test strip 1, including the graduationmarks 3 and scales 4, should be preferably printed by a printing inkwhich would not affect the wettability of the sheet material so that theamount of tear absorbed by the test strip 1 is not affected by theprinting ink. Preferably, printing is effected by an ink jet printingsystem. Black, red, blue or other desired pigments may be used in theprinting ink as long as they are not blurred by water or tear fluid. Anyone or more color-developing agents or color-modifying agents may becontained in the sheet material, or may be added to the printing ink inorder that the marks and scales can be clearly visual even when thesheet material is wetted by tear fluid. Examples of such agents includefluorescent materials, such as fluorescein sodium, rohdamine B andacrinol; water-soluble materials, such as FD & C Blue No. 1 which hasbeen used as a medical coloring agent; material which are medicamentsper se and used as injections or antimicrobial agents, such as phenolred and methylrosanilinium chloride; indicators used in the clinicaltest, such as sodium resazulin, litmus and bromthymol blue; andinorganic materials, such as cupric sulphate and cobalt chloride.

As will be apparent from the foregoing, the test strip of the inventionhas no notched portion which would weaken the sheet material and yet maybe folded precisely along the folding line prior to use. Since thegraduation marks and scales are printed while setting the folding lineas the starting line or zero point, the length of the wetted portion ofthe test strip can be precisely determined by simple visual observation.It can be judged, without confusion, whether a particular test strip hasbeen used for the diagnosis of left or right eye, since a mark for suchpurpose is provided at the end opposite to the rounded end which hasbeen inserted into the lower eye-lid of a patient.

What is claimed is:
 1. A test strip for measuring tear production,comprising a generally flat, elongated sheet material longitudinallyterminating in opposed semicircular shaped ends, said sheet having twolongitudinally extending scales of graduation marks for indicating theamount of absorbed tears, and a delineation line transverse to thelongitudinally extending scales so that one scale is on each side of thedelineation line, wherein each scale has a zero point on a further foldline near each semi-circular shaped end, said sheet having markings toindicate which eye has been tested on each scale, and said sheetmaterial being wettable by tear fluid, lacking paper powder, notsusceptible to breaking or tearing even when it absorbs tear fluid, andnot impairing the eye when in contact with it.
 2. The test stripaccording to claim 1 wherein the test strip is composed of a singlesheet of sheet material.
 3. The test strip according to claim 2 whereinat least one of said sheet material, said scale of graduation marks orsaid fold line is colored with a coloring compound selected from thegroup consisting of fluorescin sodium, rhodamine B, acrinol, FD & C BlueNo. 1, phenol red, methylrosaniliniun chloride, sodium resazulin,litmus, bromthymol blue, cupric sulphate and cobalt chloride.